Good stability and minimal osteolysis with a biconical threaded cup at 10 years.

In the literature there is no consensus on the value of threaded cementless cups. We primarily asked whether the newly constructed threaded double-cone cup without additional screw fixation would provide high survival at intermediate followup. We retrospectively reviewed 365 patients (376 hips) who underwent primary total hip arthroplasty using this cup made of pure titanium with ceramic-on-polyethylene articulating surfaces. At a minimum followup of 10.0 years (mean, 10.3 years; range, 10.0-13.1 years), 232 cups (61.7%) were available for analysis. We performed two revisions for early infection and cup breakage. No polyethylene liner was exchanged because of wear or instability. Three of the cup shells were radiographically loose at followup; one had periacetabular osteolysis. The mean liner wear rate was 0.13 mm per year. The Kaplan-Meier 10-year survivorship with revision of the cup shell for any reason was 99.3% (95% confidence interval, 96.9-99.8%) and with revision and radiographic loosening of the cup shell 98.6% (95% confidence interval, 96.0-99.5%). These intermediate results compare favorably with survivorship and periacetabular bone reaction data observed with the best cementless acetabular implant designs.